When dead bodies float
by Sapphire1112
Summary: One shot. Based in the episode 'Changes'. Nikki and Jack have a little trip down the sewer after a game of pool. I do not own the charaters or the episode 'changes'.


Nikki and Jack leaned over a map. Although she hadn't known him for long, she couldn't help but admire his dedication to the job - it was much like her own.

"The route of the River Neckinger's tributtary takes a dogleg as it moves towards the Thames." He looked thoughtful, as though a brilliant idea was forming.

"What is it?" Nikki asked.

"Hmm...what are you doing tonight?"

Nikki was taken aback - they had _only_ _just_ met after all. If he was a 'quick mover' that rang her alarm bells. Maybe that's why his face looked like that. "You're not..."

"Oh, no!" He back-tracked hastily.

He was handsome and seemed sweet enough, Nikki thought, but whoa tiger, easy!

"No, no, no, no, no, no. God, no!" Shit, what must she think of him? He had spoken without considering what he was saying... _again_! He really had to work on that. Jack thought she was lovely in every way - well from what he'd seen in the short time since they had met but he would never be forward enough to ask her out that quickly. Or arrogant enough to think someone like her would be interested in him.

Nikki relaxed. He clearly hadn't meant it to sound like that and _bless_ _him_ , he looked positively horrified by her assumption. _Cute_. "Then what did you have in mind?"

Jack looked at her mischievously.

 ***That evening...***

 _What did he have in mind?_ Beer and pool down the pub while they were waiting for the tides- and Nikki was _trashing_ him at pool! Having found out that he enjoyed cage-fighting (which was rather _stupid_ and unnecessarily _reckless_ to her mind) Nikki was on a mission. She was keen to impress Jack with her knowledge of boxing and it was working a treat. "I think Ricky Hatton's hand speed let him down. He could take Mayweather's best shot, but that's all he was doing."

 _Wow_! She _really_ knows her boxing and she's practically _annilating_ me at pool. This woman knows her stuff! "You are dangerous!"

"Thank you." This was _definitely_ working. She had clearly impressed Jack.

"How do you know about boxing?"

"Post-mortems."

Well, whatever answer he'd been expecting, it _wasn't_ that one. _Wow_! "Now _that_ is sexy!"

Nikki was definitely enjoying this. "Boxer's brains are smaller. Grey matter thinner. Do you get hit in the head a lot?"

"I try not to..."

 _Who is he kidding? Bless._ "Based on the evidence I saw..."

 _Wow_ , she's _flirting_ with me. A woman like her. "That was a one off!"

 _Yeah right, Jack! In denial, clearly. Still, it's kind of cute though!_ "Have you ever seen the brain of a person with Dementia Pugilistica?"

"I can't say I have and it's not on my list!"

It suddenly occurred to Nikki that, despite her initial _shock_ at Jack's apparent forwardness and his _horror_ at her earlier assumption, they were flirting with each other and _thoroughly_ enjoying themselves. Despite only meeting a short time ago, they were completely at ease in each other's company. "The brain strikes the inside wall of the skull, causing damage to the blood vessels, nerves and brain tissue."

"Thanks for letting me know."

 _Cheeky sod!_ "And bleeding is one of the most common causes of..."

"Let it go." He could tell that she was only trying to talk him out of it because she was concerned about him, but he enjoyed cage-fighting and it helped him. _When he won_.

"I know that you think that you're probably very...well I don't know what with your fighting..." Nikki took a swig of her beer and Jack couldn't help but admire the way she did. He was also quite _enjoying_ her telling him off - not that he was going to admit it.

He sighed."Nikki, let it go. You're not going to change me."

"It's just an ignorant thing to do."

Jack caught her eye. "You know, Doctor's have a bad habit of trying to tell everyone else how to live."

Nikki raised her eyebrows at him playfully. "Perhaps we know better."

He smirked. "Or perhaps you're just up yourself!"

Nikki laughed. It was an attractive laugh - infectious and the response he'd been looking for. "Oh, now you're _winning_ _my_ _heart_."

He blushed slightly - though she didn't appear to notice. "Yeah, that was my plan."

"Why do you do it?" Nikki asked, pretending not to notice that he was blushing.

"Release." _Bless_ _her. She's trying to understand. She wants to understand._

Nikki was surprised by his response - it didn't make much sense to her. "How much of a release can it be to get beaten up all the time?"

"Not _all_ _the_ _time_!" Jack protested reproachfully and Nikki had a sudden urge to leap over the pool table and hug him.

"Come on, look at your _face_!" she teased. He was blushing again. _Bless_.

Jack sighed again. "It does two things. One it takes away my guilt."

Nikki smirked slightly. "Try the church!" she quipped.

Jack nodded slightly - not surprised by her comment. "And two, it reminds me to have some bottle."

She was laughing again and he wasn't quite sure why this time - but oh, he _loved_ that laugh. "Why are you laughing?" She had an _incredible_ laugh.

He seemed a bit put out by her laughing, but she'd never met anyone with _so_ _much_ bottle as the man in front of her, so his second reason for cage-fighting seemed _hilarious_ to her. "Well, you definitely don't seem short on that."

Nikki took another swig of her beer as he smiled softly at her. Despite only knowing her a short while, Jack couldn't help but feel fondly towards the woman in front of him. "It's a work in progress."

"What are you scared of?"

He shook his head. He didn't really want to go into it. "It's a _long_ story about an old job. He checked his watch and chucked the pool cue on the table. "It's time."

 ***10 minutes later...***

Nikki and Jack walked along the gravel at the edge of the Thames. She glanced over her shoulder at him. "Her body was found here, wasn't it?"

"yep"

"And we know that she wasn't thrown into the river alive because her lungs would have been filled with water so..." She glanced back at him again. He was now on his hands and knees on the gravel, examining something over by the wall. "What is it?"

"Combined sewer overflow. The outlet of the Neckinger's tributary. One of London's underground rivers. When it rains too heavily, it takes the sewage overflow." He explained as she crouched down next to him.

" _Rat_ _faeces_ in her hair! Asphyxiated by _sewage_." Nikki exclaimed.

"It was raining hard. The water rises. Deanna's body is pushed into the combined sewer."

"Force of the water pushed her along." She agreed, noticing how much _stronger_ his accent became when mixed with enthusiasm.

"Smashes her body against the drain pipes and metal bars in the overflow pipe until it reaches the Thames." Jack continued.

"So her body was found here but she died..."

"In there." He finished as they both looked towards the combined sewer.

Nikki and Jack headed off the gravel, up to the roadside. They walked to the railings which surrounded the place that had been crawling with forensics earlier, all to no avail. The forensic team from earlier had found nothing. Jack reached the railings first. He was _convinced_ that he - and Nikki could be much more successful. "This is where they were picking up her mobile signal from."

He chucked his bag over, following it with a 'James Bond' style leap over the railings. In his enthusiasm to solve the case - and _possibly_ an underlying intention of impressing Nikki, he had failed to notice that there was a gap in the railings right next to where he had preformed his leap. A gap which Nikki now easily slid through with a smirk. " _O-k_ " Jack responded sheepishly to her smirk.

Nikki indicated at the ground. "Manhole...and another here."

Jack shook his head. These were no good. "You need a key to open these."

They walked along the path for a while, eventually chancing upon a manhole that had been opened for maintence purposes. Jack shone his torch down it with a triumphant look at Nikki. She caught his expression and followed the beam of his torch, before glancing back at him with a look of _utter_ _disbelief_. Surely he wasn't suggesting they spent their evening searching a _sewer_?! " _You're not going to._.." He nodded, suppressing the urge to chuckle at her shocked expression - although his eyes were still laughing. " _Well, I'm not going_..." Nikki shot at him. Jack's eyes changed from amused to pleading. " _No, there is no chance!_ "

 ***Under the ground...***

Jack was amazed at how _easily_ he had been able to change her mind. He had expected at least a _little_ _bit_ of resistance. In fact, _so had she_. Squeaking echoed through the sewer. "Was that a rat?"

Jack looked back at her. "Yeah, _huge_ one." He shone his light up a hole in the ceiling of the tunnel. "Leads to a manhole." He met with a metal bar at the end of their tunnel, which prevented them from going any further. The tunnel joined on to the main sewer tunnel. Jack's long legs made easy work of stepping over the bar. He turned and offered her his hand. Jack was nothing, if not a gentleman. "Here you go" he said, helping over the bar.

Some kind of distant knocking resounded around the tunnel. Not knowing what it was made Nikki shudder. "Did you hear that?!"

He looked back at her. "What?"

"What do we do if it floods?"

 _Bless her._ "Run."

She thought he was joking. "Ha ha!" Nikki responded sarcastically.

"I'm serious." Jack turned back to leading along the tunnel, grinning mischievously at Nikki's shocked face.

How the _hell_ had he got her down here? She usually took _a_ _lot_ _more_ persuading. _No one_ could talk Nikki Alexander into something she didn't want to do. Not her - in fact she _prided_ herself on being able to stand her ground, _especially_ with men. Yet _Jack_ _Hodgson_ had given her one look with those pleading eyes and she'd _melted_. Now she was doing exactly what he wanted. _What the hell_? Her thoughts were broken by another disturbing sound. Rushing water. Shit - this tunnel was _actually_ flooding. Damn him. "Jack?"

"Huh?" Far from being amused this time, Jack wanted to reassure her. He would keep her safe. "Oh, it's the River Neckinger. Must be just above us. All the sewage converges here. If there's too much water it rises to the overflow." In earnest, he had wanted to reassure her, but he had gone a bit far.

 _"Shut up!"_

With sudden horror, Jack realised his mistake. "I'm wrong. Shit! I'm wrong." He was wrong and now she would never trust him again. What if they drowned down here, because he'd got it wrong?

"What are you wrong about?"

"If she's just been murdered her body won't float. Doesn't work. How could I be so stupid?! Dead bodies don't float! If it won't float, it can't rise to the overflow. Shit."

Jack gave a defeated sigh and Nikki really felt for him. He looked so lost now that his earlier enthusiasm had been extinguished and she might have been mistaken but she was sure she saw concern in his eyes too. Concern for her and the situation he had brought her into. She would have to make the best out of it - just to make him feel better. She checked her phone. "I've got a signal, turn your light off." Nikki dialled Deanna's number and waited.

Jack turned his light off at her request. She wasn't cross with him for bringing her down here as he'd expected. Not at all. In fact she was trying to _help_ \- trying to _make_ _him_ _feel_ _better_. A phone rang somewhere ahead of them and Jack spotted it. He turned his light back on. "She was kiledl and the murderer threw her gear into the sewer. But where was she killed?"

Nikki moved past him along the tunnel. Eventually, she crouched down, and picked up the bag she'd just seen lodged in the pipes. She opened it and examined the contents. "Here. She died in here." She held up an inhaler.

Jack shook his head, his accent coming across stronger than ever. "It takes 48 to 72 hours for a body to decompose enough to trap gases so it'll float. _How_ did the body rise to the overflow?"

Nikki looked thoughtful. "When she was hit by the car, her leg was broken, she was knocked unconscious. Yes?"

Jack nodded. "Yes."

As she continued, Jack noticed the captivating way her eyes were flashing as she cracked the case for him. "But when she regains consciousness, she's in the tunnel in the dark...in terrible pain. She has trouble breathing, so she uses her _inhaler_. She hears the water rushing, sees the tunnel filling, there is _no_ _escape_." Jack found he was unable to take his eyes off Nikki as she carried on with her explanation. "The water's filling fast, so she tries to stay afloat, but as she rises in the chamber, she desperately... _gasps_ for air. She takes in a mouthful of scum floating to the top, human detritus and her airways are _blocked_. The water buffets her, smashing her skull, breaking her bones and then disposes of her in the Thames. There is _no_ water in her lungs because her Oesophagus and Trachea are _obstructed_."

Nikki walked back over to Jack and stopped in front of him. He still couldn't take his eyes off her. This woman's mind was _amazing_! "The _steroids_ in the inhaler allow her to fill her lungs to capacity. Gases trapped in the lungs, making them buoyant. _She's_ _dead - she floats_." Nikki finished triumphantly. Jack stared at her in _awe_. He'd brought her down here, intent on giving her an experience she'd _never_ _had_ _before_ and she had gone and found the answer he couldn't.

 _Nikki could give as good as she got._


End file.
